# Developer & data tools

> A network of 9 focused, deterministic tools. Every tool has a human page, a JSON API, an OpenAPI description and an MCP tool that all return the same result (inputs, result, units, assumptions, sources, timestamps).

## Machine interfaces
- Tool catalog (JSON): https://developer.usefulweb.site/api/v1/tools
- OpenAPI (all tools): https://developer.usefulweb.site/openapi.json
- MCP server (all tools + workflows): https://developer.usefulweb.site/mcp
- Pick a tool for a natural-language request: POST https://developer.usefulweb.site/api/v1/tools/prompt-to-tool-router/calculate {"request": "..."}

## Tools
- [HeaderLens](https://headerlens.usefulweb.site/): Is a website down? Multi-region status, redirects, TLS and security headers. API: POST https://developer.usefulweb.site/api/v1/tools/headerlens/calculate
- [Accessibility Snapshot](https://a11ysnapshot.usefulweb.site/): Static WCAG 2.2 snapshot of a page: findings by severity, evidence and manual checks. API: POST https://developer.usefulweb.site/api/v1/tools/a11y-snapshot/calculate
- [CiteShape](https://citeshape.usefulweb.site/): Paste a DOI, ORCID iD, ISBN or arXiv ID: validated, resolved, and formatted as APA, BibTeX and RIS. API: POST https://developer.usefulweb.site/api/v1/tools/citeshape/calculate
- [DataFresh](https://datafresh.usefulweb.site/): Is this dataset or API still fresh? Newest record, update cadence check and schema drift. API: POST https://developer.usefulweb.site/api/v1/tools/datafresh/calculate
- [FileFit](https://filefit.usefulweb.site/): Can this app open, edit or convert that file format? Verified facts with sources. API: POST https://developer.usefulweb.site/api/v1/tools/filefit/calculate
- [LocaleKit Country Format Rules](https://localekit.usefulweb.site/): Address form fields, postal-code regex, calling code and date formats for any country. API: POST https://developer.usefulweb.site/api/v1/tools/localekit/calculate
- [RuleDate Deadline Calculator](https://ruledate.usefulweb.site/): Business-day and deadline maths with public holidays and a step-by-step rule trace. API: POST https://developer.usefulweb.site/api/v1/tools/ruledate/calculate
- [TimeFair Meeting Planner](https://timefair.usefulweb.site/): Find fair meeting times across time zones, with DST-exact local times and rotation. API: POST https://developer.usefulweb.site/api/v1/tools/timefair/calculate
- [UnitProof Unit Calculator](https://unitproof.usefulweb.site/): Unit maths you can audit: dimension check, exact factors and a full derivation tree. API: POST https://developer.usefulweb.site/api/v1/tools/unitproof/calculate

## Workflows